Just because something has a rarity in one country doesn't mean that similar rarity in another means they should command the same price. The gap MAY narrow or close completely -- we don't know. But I wouldn't extrapolate trends from 1921.
Where/how does one go about selling a considerable number of higher-grade "world hot-market" (foreign) silver coins that are unfortunately raw/ungraded...? Most are 19th century and early-mid 20th century British, Canadian, Australian and European (Austria, Poland, Czech, Italy, etc), with some varied others plus Panamanian, Latin/Spanish and similar. I've waited too long and now my limited retirement budget just doesn't have room for grading fees...even 10 or 15 per month...which would take forever, anyway. Seems everything must be TP-graded nowadays...understand for the most part. That said, I know grading, and many if not most are MS, and most that aren't are AU. One of my better coins is a 1927 British Crown/proof. Many Canadian $1 and 50c of the 1930s-1960s including a 1947 50c w/maple leaf. I have no photos (I don't/can't do them, nor eBay, etc.) but have compiled extensive lists and descriptions by country that I can email. If anyone is within reasonable driving distance of southern rural Indiana and seriously interested, I'd be willing to meet with them here/there, halfway, etc, to see some of them. I need to sell my entire life-long collection to include my U.S. coins as well, for health and retirement reasons. Thanks for any suggestions, experiences.
You could consign them to Auction Houses in US like Heritage/ Stacks/ CNG/ Goldbergs. All auction firms are looking for high grade World coinage. John